1. Field of the Invention
The present invention relates to a telescoping system for selectively extending and retracting telescopic sections of a multi-section telescoping structure with respect to one another; and more particularly, to a telescoping system with multiple single-stage telescopic cylinders.
2. Description of Related Art
Many prior art telescoping systems include multiple single-stage telescopic cylinders or a single multi-stage telescopic cylinder for extending and retracting multi-section telescopic structures such as multi-section booms. A multi-stage telescopic cylinder includes a plurality of cylinders and pistons arranged in a telescopic manner, one within the other. In a telescoping system which includes multiple single-stage telescopic cylinders, the telescopic cylinders are hydraulically connected in series. U.S. Pat. No. 4,733,598 to Innes discloses such a telescoping system.
Unfortunately, telescoping systems such as Innes do not allow independent control over retraction and extension of each single-stage telescopic cylinder. Instead, the extension and retraction of the telescoping system is predetermined. Namely, the order in which the single-stage telescopic cylinders extend and retract is predetermined. Furthermore, each telescopic cylinder in the system fully retracts or extends. Accordingly, systems such as Innes are not flexible, and each time a user wants to change, for example, the order in which the telescopic cylinders extend and retract, a different telescoping system is required.